Some myths are better to indulge

The other evening (middle-aged speak for "months ago"), sitting having one of my favourite repasts - slow, bland, achingly solitary - at the OK Chinese restaurant on the Wandsworth Road, I found myself shamelessly eavesdropping on the conversation of the couple at the next table. They were a father and son in their late forties and late teens respectively. They had a large-boned assurance and an ease with one another I found instantly attractive - how else to explain my moment of madness?

After all, a native Londoner, I revile above all things the folly of talking to strangers. Anyway, there was this attraction, and there was what they were saying: the son jollily expounding to his dad that, "In the 1500s, or maybe the 1700s - I'm not sure which - there was a huge flood in London, the whole city was under water, something like 25,000 people were drowned."

Panic on the streets

The older man demurred: "No, I can't believe that! I'm sure I'd've heard about it . . ." But the son persisted in his contention that the city had been completely deluged at some indeterminate point in the past, with a concomitant huge loss of life. It was at this point that I could no longer forbear, and leapt in with a potted version of the account of the 1524 flood-that-never-was, as told by Charles Mackay in his Extraordinary Popular Delusions and the Madness of Crowds.

According to Mackay, a mania for prophecy conjoined with several soothsayers predicting a catastrophic high tide on the Thames for 1 February 1524 - the result was a mounting and wholesale panic.

As the appointed day neared, thousands fled their homes and set up encampments on the heights of Hampstead and the North Downs. The prior of St Bartholomew was so alarmed, that he had a well-provisioned stockade erected at Harrow-on-the-Hill to which he retired with a few close friends - shades here of Poe's tale "The Masque of the Red Death".

As we know, no flood occurred, and the populace trailed home feeling shamefaced in the way we all do after succumbing to asinine groupthink.

I was momentarily bowled over by the notion that this young chap, circa 2011, might be retelling not a piece of bona fide history learned from some sub-Schama at school, but a folk tale that was still embedded in the popular unconscious of Londoners and that had, over the centuries, acquired the verdigris of veracity.

We're all familiar with the phenomenon of the urban myth, which, despite spawning sodden stacks of toilet books in the past few decades, still continues to culture itself using the minds of the credulous as a substrate.

A recent one (middle-aged speak for "some years ago") took the form of a round-robin email sent on by a friend who's a senior editor at a national newspaper - and really should have known better. The gist of this scare story was that night-time drivers in sarf London shouldn't flash their headlights if flashed by another car, because they would then be chased by the flasher and gunned down in cold blood.

I pointed out to my daffy pal that the spread of this delusion exactly coincided with a local upsurge in gun crime; moreover, didn't she think it strange that the myth was being transmitted between white middle-class professionals via email, when all the shootings were black-on-black and confined to the lumpenproletariat?

Ducking the issue

But to return to the brackish matter in hand. My fellow diners heard me out, and then the dad mused: "Well, come to think of it, I suppose London must've flooded at some point - or else they wouldn't've built the Thames Barrier." I was about to explain to him that while London had been subjected to quite devastating floods - notably in 1953 - the loss of life had been in the low hundreds, and that furthermore the Thames Barrier had been built as an antediluvian measure, rather than après le déluge. But then I thought better of it and put my face back in my duck with ginger and spring onions.

Why? Well, you can't win 'em all - and besides, I was reminded of how I had shared such moments of baseless conviction with my own late father. Our joint delusion had seemed altogether believable at the time, and we had chatted long into the night outlining the specifics of what, in later years, I came to realise was never ever going to happen.

Will Self is the author of seven novels, six collections of stories and five collections of non-fiction. His most recent novel is The Butt. He writes the Madness of Crowds column for the New Statesman as well as the Real Meals column.